I. Field
The present disclosure relates generally to communication, and more specifically to techniques for transmitting data in a wireless communication system.
II. Background
In a wireless communication system, a transmitter (e.g., a base station or a terminal) may utilize multiple (T) transmit antennas for data transmission to a receiver equipped with multiple (R) receive antennas. The multiple transmit and receive antennas may be used to increase throughput and/or improve reliability. For example, the transmitter may transmit T symbols simultaneously from the T transmit antennas to improve throughput. Alternatively, the transmitter may transmit the same symbol redundantly from all T transmit antennas to improve reception by the receiver.
The transmission from each transmit antenna causes interference to the transmissions from the other transmit antennas. In some instances, improved performance may be achieved by transmitting fewer than T symbols simultaneously from the T transmit antennas. This may be achieved by selecting a subset of the T transmit antennas and transmitting fewer than T symbols from the selected subset of transmit antenna(s). The transmit antenna(s) that are not used for transmission do not cause interference to the transmit antenna(s) that are used for transmission. Hence, improved performance may be achieved for the selected subset of transmit antenna(s).
Each transmit antenna is typically associated with certain peak transmit power that may be used for that antenna. The peak transmit power may be determined by a power amplifier used for the transmit antenna, regulatory constraints, and/or other factors. For each transmit antenna that is not used for transmission, the transmit power for that antenna is essentially wasted.
There is therefore a need in the art for techniques to more effectively utilize the transmit power available for the transmit antennas.